/*
 * Copyright (C) 2012 Roman Yakovenko <erelus@gmail.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is furnished to do
 * so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

package com.fuzzy.functions;

import com.fuzzy.core.Function;
import com.fuzzy.core.FuzzyPoint;

public class Trapezoid implements Function {

    private FuzzyPoint start;
    private FuzzyPoint end;
    private FuzzyPoint peak1;
    private FuzzyPoint peak2;

    public Trapezoid(double start, double end, double peak1, double peak2) {
        assert (start < peak1);
        assert (peak1 < peak2);
        assert (peak2 < end);

        this.start = new FuzzyPoint(start, 0D);
        this.end = new FuzzyPoint(end, 0D);
        this.peak1 = new FuzzyPoint(peak1, 1D);
        this.peak2 = new FuzzyPoint(peak2, 1D);
    }

    @Override
    public double getM(double value) {
        if (value >= start.getX() && value < peak1.getX()) {
            double tanAlpha = Math.tan(1D / (peak1.getX() - start.getX()));
            return tanAlpha * (value - start.getX());
        }

        if (value >= peak1.getX() && value <= peak2.getX()) {
            return peak1.getY();
        }

        if (value > peak2.getX() && value <= end.getX()) {
            double tanBeta = Math.tan(1D / (end.getX() - peak2.getX()));
            return tanBeta * (end.getX() - value);
        }

        return Function.NOT_IN_SET;
    }

    @Override
    public FuzzyPoint[] toPoints() {
        return new FuzzyPoint[]{start, peak1, peak2, end};
    }
}
